Conventionally, in order to improve adhesion properties to a core cloth, water-resistant washability, and dry cleaning resistance, there has been suggested a hot melt adhesive composed of a thermoplastic polyurethane resin in which a difference between the softening start temperature and the softening end temperature, and the softening start temperature are set to specified ranges, the temperatures being according to a needle-penetrating mode of thermomechanical analysis. It is stated that this adhesive is also used as a material for slush molding (see, for example, Patent Document 1).
Regarding resin particles used for powder coating, electrophotographic toner, and electrostatic recording toner, there have been suggested urethane resin particles which are meltable at low temperatures by adjusting the crystallinity, the melting point, and the molecular weight. It is stated that the particles are also used as a material for slush molding (see, for example, Patent Documents 2 and 3).
In recent years, as an instrument panel which is an interior part of an automobile, a slush molded product is used. In order to achieve low cost and high cycle of slush molding as well as long life of a mold, molding at low temperatures is demanded (see, for example, Patent Document 4). On the other hand, a cleavage is located in the instrument panel so as to expand an airbag stored under the instrument panel. For processing of the cleavage, from the viewpoint of design, a method of slitting the rear surface of the slush molded product by using a cutter is employed. However, in the region of high temperatures, the slit on the rear surface is fused by heat and disappears, so that the airbag may not open normally. Therefore, a slush molding material with excellent heat resistance is demanded (see, for example, Patent Documents 5 and 6).
In automobile parts, there is a need for weight saving for the purpose of improving fuel consumption. As a measure for achieving weight saving of interior materials of an automobile, it is considered a measure of making a slush molded body into a thinner form. However, the thinner form reduces mechanical properties of the molded body, so that it is necessary to provide stronger mechanical properties.